1. Field of the Invention
The present invention relates to the processing of liquids and chunky particulates of fruits, vegetables or meats. More particularly, the invention relates to a continuous aseptic system for processing individual can size units of predetermined amounts of liquid and solid ingredients.
2. Description of the Prior Art
The most widely used equipment for the continuous processing of such materials under sterile conditions is the swept or scraped surface heat exchanger (SSHE). This type of exchanger uses a cylindrical barrel fitted with a rotating dasher, the blades of which bear against the internal surface of the barrel. Heating or cooling of the barrel is affected by introducing the heat exchange medium, i.e. steam, water, brine or refrigeration, into a jacket which surrounds the exterior of the barrel. The rotating motion of the blades against the internal surface of the barrel continually exposes the internal surface of the barrel to new product. Since the barrel has a comparatively small heating surface, the temperature of the heat or cold exchange medium is generally quite high or low. This high temperature differential imparts thermal shock to the product as it engages the interior wall of the barrel which generates unwanted cooked flavor to the final product. The higher temperature necessary for sterilization also renders the solid particulates very sensitive to mechanical damage from the continuous impact with the fast rotating blades resulting in a loss in the visual appeal of the solid particulates.
In order to minimize impact on the particulates, the liquid viscosity must be very high in order to prevent separation of the particulates. This is accomplished by the addition of starch which is generally disproportionate to the desired effect on the finished product due to the mechanical destruction of the starch by the quickly moving blades.
In the processing of liquid and solid particulates, it is difficult to prevent the separation of the liquid from the solid. This is further aggravated where large solid particulates are being processed which requires additional heat exchange time for the heat to reach the center of the particles often resulting in overheating of the supporting or carrying liquid.
Another system available to process and sterilize liquid solid products consists of a double cone aseptic processing vessel using both direct and indirect heating and cooling. This vessel batches solids separately from a second parallel system which continuously sterilizes the sauce. The rotating double cone vessel imparts at high temperature a tumbling action to the solids which mechanically damages them and can affect their appearance. The batching action precludes a continuous aseptic processing as a new solid load has to be introduced into the vessel breaking the vessel aseptic condition. This is a fairly expensive system since a large mass, up to one to two tons, is processed in each batch. The batch type system requires separation of the solid and liquid processing complicating the system in requiring additional aseptic vessels. Since the process is not continuous its use in commercial applications has been limited.